Spool File With Date/Time Name

i use to created spool file With Date/Time Name

SET TERMOUT OFF
COLUMN today_ddmmyyyy_col NEW_VALUE today_ddmmyyyy
SELECT TO_CHAR ( SYSDATE, 'DDMMYYYY') AS today_ddmmyyyy_col
FROM    dual;
SET TERMOUT ON
SPOOL ticket_&today_ddmmyyyy..log